Kinetically Assisted Potential Sputtering of Insulators by Highly Charged Ions

A new form of potential sputtering has been found for impact of slow ( $\le 1500\mathrm{eV}$) multiply charged Xe ions (charge states up to $q=25\mathrm{}$) on ${\mathrm{MgO}}_x$. In contrast to alkali-halide or ${\mathrm{SiO}}_2$ surfaces this mechanism requires the simultaneous presence of electronic excitation of the target material and of a kinetically formed collision cascade within the target in order to initiate the sputtering process. This kinetically assisted potential sputtering mechanism has been identified to be present for other insulating surfaces as well.